Wonder Creek IA 01-TRK-219

mouth (S19 T97N R9W Winneshiek Co.) to confluence with unnamed tributary in S24 T97N R10W Winneshiek Co.

Open Data Collection Period Modal

For purposes of developing stream/river water quality assessments for integrated reporting, three years of water quality data are typically used for both conventional pollutant parameters (e.g., indicator bacteria) and the less frequently monitored toxic parameters (e.g., toxic metals). Since the 2004 IR cycle, DNR has used a three-year data gathering period for streams, rivers, and beaches. For most assessments, the use of three years of data increases the number of samples upon which the decision on use support is based and helps address the problem of weather-related year-to-year fluctuations in water quality.

Due to the lower sampling frequency in Iowa’s ambient lake, biological, fish kill, and fish tissue monitoring programs, five years of data are used for developing IR assessments and for identifying Section 303(d) listings.

Data Type	Data Timeframe
Beach Sampling Data	CY 2014 - 2016
Stream/River Water Quality Data	CY 2014 - 2016
Lake Water Quality Data	CY 2012 - 2016
Biological Sampling Data	CY 2012 - 2016*
Fish Kill Data	CY 2012 - 2016
Fish Tissue Sampling Data	CY 2012 - 2016
Continuous Dissolved Oxygen Sampling Data	CY 2012 - 2016
*Biological sites sampled in both 2011 and 2015 were also assessed.

Open Segment Map
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Cycle: 2018
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 7/24/2019 8:26:55 AM
Updated: 7/24/2019 8:27:16 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2014

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 (primary contact recreation) uses remain assessed (monitored) as “not supported” (IR 5p) due to levels of indicator bacteria that exceed state water quality criteria. The Class B(WW2) aquatic life uses are assessed (monitored) as “fully supported” (IR 2a) based on results of water quality monitoring from April 2012 to November 2014. The data used for this assessment are from monitoring conducted from April 2012 to November 2014 as part of the Turkey River Watershed project at station WON-10 at Main Street/W14 (STORET station 15960020).

Assessment Explanation

The presumptive Class A1 (primary contact recreation) uses remain assessed as "not supported" based on levels of indicator bacteria that exceeded state water quality criteria. Based on the approximately eight monthly samples collected during the recreation seasons of 2012, 2013, and 2014, the geometric means at station WON-10 are as follow: 976 orgs/100 ml, 1,967 orgs/100 ml, and 286 E. coli orgs/100 ml., respectively. All three geometric means exceed the Class A1 geometric mean criterion of 126 orgs/100 ml. Seventeen of the combined 24 samples (71%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and DNR’s assessment/listing methodology, if a recreation season geometric mean exceeds the respective water quality criterion, the contact recreation uses are "not supported" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as “impaired.”

Results of chemical/physical water quality monitoring from 2012 and 2014 do not suggest impairment of the Class B(WW2) aquatic life uses. Monitoring at station WON-10 (STORET station 15960020) showed no violations of Class B(WW2) water quality criteria for dissolved oxygen (24 samples), ammonia (15 samples), pH (23 samples), temperature (24 samples), or chloride (16 samples) in the samples analyzed. These results suggest “full support” of the Class B(WW2) aquatic life uses.

Monitoring and Methods

Assessment Key Dates

4/4/2012

Fixed Monitoring Start Date

11/5/2014

Fixed Monitoring End Date

Methods

240

Non-fixed station physical/chemical (conventional + toxicants)

420

Indicator bacteria monitoring